Aerial system for radio beacons



June 6, 1944. P. P. GAMl-:T 2,350,747

AERIAL SYSTEM FOR RADIO BEAQONS Filed May 9, 1942 Patented June 6, 1944AERIAL SYSTEM FOR RADIO BEACON S Pierre Paul Garnet, Paris, France;vested in the Alien Property Custodian Y Application May 9, 1942, SerialNo. 442,374

In France May 29, 1941 Y (ci. .25o-11) 2 Claims.

This invention relates to improvements in aerial systems for radiobeacons.

It relates more particularly to an aerial system for radio beacons whichprovides foreflecting in a novel manner a well known method of radiodirection finding.

In the known aerial systems for radio beacons it is necessary that thedistance between the three aerials providing for the transmission of theradio-electric fwaves in la preferential direction shall be equal to aquarter of the wave length, which offers the disadvantage of requiring acumbersome device which can be mounted only with difculty on a rotatingplate for obtaining a rotating beam.

Furthermore, these systems require the use of at least three aerials.

The present invention has for its object to remedy these disadvantagesand to provide a device with two aerials which are set very closetogether, the said device permitting to obtain a radiation in apreferential direction and in a given range of frequencies.

On the other hand, if it is desired to obtain a circular pattern ofradiated beam, the known aerial systems for radio beacons necessitate afourth aerial, which still further increases the space required by thesystem and its cost.

Another object of the present invention is also to do away with thisdisadvantage by providing an aerial system for radio beacons whichnecessitates no special additional aerial for the circular radiatingbeam.

An improved aerial system for radio beacons permitting to attain theabove mentioned objects possesses the characteristic features whichappear from the following description and especially from the appendedclaims.

Systems made according to the invention are shown diagrammatically inthe appended drawing, in which:

Figures 1 and 2 are radiation diagrams of the systems;

Figures 3 and 4 are circuit diagrams of the system;

Figure 5 is a View of a system for obtaining a rotating radiationpattern by rotating the antennas on a rotating plate, and

Fig. 6 shows an arrangement for selectively obtaining a desired one of avariety of radiation patterns.

The diagram of Figure 3 comprises an aerial I which is supplied directlyby the transmitting station 3 by means of a transmission line II.

An aerial 2 is supplied by the same transmitting station 3 by means ofthe transmission line and of a phase shifting unit 5 so that the supplyvoltage of this aerial is shifted in phase by a certain value withrespect to that of the other aerial I.

'I'he operation of the device is identical to that of the device whichis generally used for obtaining the radiation pattern transmitted in apreferential direction and in which a system of two aerials is usedwhich are spaced from one another by a quarter of a wave length, thisspacing effecting the difference of course giving the phase shiftingwhich is necessary for the operation of the system and permitting toobtain the radiation diagrams of Figures 1 and 2.

'I'his phase shifting obtained by a difference of course is effected, inthe device according to the present invention, through a phase shiftingcircuit which permits by adjusting the phase in a convenient manner toset the aerials at any distance from each other. Thus a radiationdiagram with a radiation pattern shown by the cardioid 6 is obtained,the axis of the aerials being at 1.

This device permits to easily set up all the relations which arenecessary for the operation of apparatus such as rotating radio beaconsor beaconing devices for a, channel. namely:

(1) Reversing of the direction of radiation;

(2) Obtaining a rotating radiation beam;

(3) Obtaining a circular radiation pattern.

Referring to Fig. 4, the desired direction of the radiation is obtainedby reversing the supply connections of the aerials I and 2.

The aerial I is then supplied through the medium of the phase shiftingcircuit 5 and the aerial 2 is supplied directly. For carrying out thisoperation one may provide a reversing switch 8 which effects the changesof connections which are necessary for directing the radiating beamsometimes in one direction and sometimes in the other, by reversing thesupply connections of the two aerials.

For obtaining a rotating directional radiation beam the aerials aremounted on a plate I0 revolving about an axis II, and are connected tothe transmitter in convenient manner.

The rotation of this plate I0 eiects the rotation of the directionalradiating beam.

This system offers the advantage that it can be mounted on a plate ofsmall dimensions since the aerials can be very close to each othercontrary to the known systems where the distance between both aerialsmust be equal to a quarter of a wave length.

A circular radiating beam is obtained by feeding the aerials I and 2 inphase.

Such an arrangement is shown in Fig. 6, which' shows a modification ofthe arrangement of Fig.

`direct to the transmitter, and the other aerial to the phase shifter,in either combination desired. The switchv I8 is arranged ,andl wired toprovide the third operating position.l When the Y transmitter 3 isconnected directly to both aerial I and aerial 2 without passing throughthe phase shifter 5 at all, the aerials are fed in phase, a nd.

there is produced a circular radiation pattern.

In Fig. 6, the aerials I, 2, the transmitter 3, the transmission line 4,and the phase shifter-5, correspond to the similar elements of Figli,and the rotating table I0 carrying aerials I and 2 correspondstorotatingA table I0 OtLFig. 5. AIn the three-position switch I8, theblade terminals I9 and 20 are respectively connectedto aerials Iand 2.`The outside contact terminals 2! and 24 are connected. together and tophase shifter 5. yThe inner contact terminals 22 and 23 are connectedtogether and through transmission line :d directly to transmitter 3. Inits extreme right position the switch IB connects transmitter 3 directlyto aerial I, and connects through phase shifter `5 to aerial 2, while inthe extreme left positionA of switch yI8 the connections to the aerials!and 2 are reversed.` In its middle position, switch I8 connects bothaerials I andV 2 in phase directly Ato transmitter 3 throughtransmission line 4.v .l Y

With respect to theA known systems this de- Y vice offersv the advantagethat it requires n0 pattern.

special "aerial vfor obtaining a circular radiation pair of aerialsmounted Very close together relative to a quarter wavek length, a sourceof highifreq'uency oscillations, a rst transmission line` connected to arst'one ofsaid aerials, a

Y Y second transmission line connected to a second one of said'aerials,ra phase shifting impedance Since these aerials Iavnd 12 are set atasmall K distance from each other, they form -a unit whichV is equivalentto a single aerial equallyin all directions.

and thus .radiate n unit, and selective connecting means forvselectively connecting either the both of said trans-V mission lines tosaid source without passing through said phase shifting unit, orVconnecting either one of said transmission lines to said source throughsaid phase shifting unit Vand,

at the same time connecting the other one of saidtransmission linesdirectly to said source .v

Without passing l through said phase n shifting 2. In .an aeria systemfor radio vbeaconsVa pair of. aerials, va rotatable plate, saidgaerialsbeing mounted on said plate very close together relativeto aquarterfwave length, a source Yof high-frequency oscillations, ai'lrsttransmission line connected to a first onevof said aerials, asecondtransmission line connected toa second one of said aerials, aphase shiftingimped-ance unit, and selective :connecting means forselectively connecting either the both ofV said transmission lines tosaid source without passing through saidphase shifting unit, orVconnecting either one of said transmission lines -to said source throughsaid phase shifting unit and at the same time 1connecting the other one'of said transmission linesldirectly tosaid source with- Vout passingthrough saidfphase shifting unit.v

andat all times maintaining both of said aerials energized from'saidsource. l

A. ripiani: PAUL GAMET.

